HL-1 cells express an inwardly rectifying K+ current activated via muscarinic receptors comparable to that in mouse atrial myocytes

An inwardly rectifying K^+ current is present in atrial cardiac myocytes that is activated by acetylcholine (I_{KACh}). Physiologically, activation of the current in the SA node is important in slowing the heart rate with increased parasympathetic tone. It is a paradigm for the direct regulation of signaling effectors by the Gβγ G-protein subunit. Many questions have been addressed in heterologous expression systems with less focus on the behaviour in native myocytes partly because of the technical difficulties in undertaking comparable studies in native cells. In this study, we characterise a potassium current in the atrial-derived cell line HL-1. Using an electrophysiological approach, we compare the characteristics of the potassium current with those in native atrial cells and in a HEK cell line expressing the cloned Kir3.1/3.4 channel. The potassium current recorded in HL-1 is inwardly rectifying and activated by the muscarinic agonist carbachol. Carbachol-activated currents were inhibited by pertussis toxin and tertiapin-Q. The basal current was time-dependently increased when GTP was substituted in the patch-clamp pipette by the non-hydrolysable analogue GTPγS. We compared the kinetics of current modulation in HL-1 with those of freshly isolated atrial mouse cardiomyocytes. The current activation and deactivation kinetics in HL-1 cells are comparable to those measured in atrial cardiomyocytes. Using immunofluorescence, we found GIRK4 at the membrane in HL-1 cells. Real-time RT-PCR confirms the presence of mRNA for the main G-protein subunits, as well as for M2 muscarinic and A1 adenosine receptors. The data suggest HL-1 cells are a good model to study IKAch

Atrial arrhythmogenicity of KCNJ2 mutations in short QT syndrome: Insights from virtual human atria

Gain-of-function mutations in KCNJ2-encoded Kir2.1 channels underlie variant 3 (SQT3) of the short QT syndrome, which is associated with atrial fibrillation (AF). Using biophysically-detailed human atria computer models, this study investigated the mechanistic link between SQT3 mutations and atrial arrhythmogenesis, and potential ion channel targets for treatment of SQT3. A contemporary model of the human atrial action potential (AP) was modified to recapitulate functional changes in IK1 due to heterozygous and homozygous forms of the D172N and E299V Kir2.1 mutations. Wild-type (WT) and mutant formulations were incorporated into multi-scale homogeneous and heterogeneous tissue models. Effects of mutations on AP duration (APD), conduction velocity (CV), effective refractory period (ERP), tissue excitation threshold and their rate-dependence, as well as the wavelength of re-entry (WL) were quantified. The D172N and E299V Kir2.1 mutations produced distinct effects on IK1 and APD shortening. Both mutations decreased WL for re-entry through a reduction in ERP and CV. Stability of re-entrant excitation waves in 2D and 3D tissue models was mediated by changes to tissue excitability and dispersion of APD in mutation conditions. Combined block of IK1 and IKr was effective in terminating re-entry associated with heterozygous D172N conditions, whereas IKr block alone may be a safer alternative for the E299V mutation. Combined inhibition of IKr and IKur produced a synergistic anti-arrhythmic effect in both forms of SQT3. In conclusion, this study provides mechanistic insights into atrial proarrhythmia with SQT3 Kir2.1 mutations and highlights possible pharmacological strategies for management of SQT3-linked AF

Biodiversity and complementary feeding practices of children in the north west region of Cameroon

Data from Northwest Region (rural) agro-ecological zone is Tropics lowland, warm Tree Crop farming system. West-African food composition table is used Stadlmayr B, et al. (2012) West-African Food Composition Table. (Rome), p 148. Species consumed were identified using ICRAF data for Cameroun and World Vegetable Centre, Yaoundé, Cameroon Only mothers with children between 12-23 months were interviewed. Households were first visited to inform the mother/caregiver on the study background and objectives after which consent to participate was asked by reading out a consent form. Only upon agreement and subsequent signing of the form, an interview was conducted. The study was approved by ethics Clearance Committee, Yaoundé, Cameroon. Food and drink intake was assessed using a 2 day interview-administered 24-hour recall. Composition of food was obtained from FAO (2012). West African Food Composition Table, FAO, Rome, Italy and species were identified at World Vegetable Centre, Yaoundé, Cameroo

Ethnomycological study in the Kilum-Ijim mountain forest, Northwest Region, Cameroon

Abstract Background Majority of the people in rural areas depend on traditional fungi-based medicines to combat different illnesses. This ethnomycological survey was undertaken to document the traditional knowledge of mushrooms among the communities in the Kilum-Ijim mountain forest reserve. Although macrofungi are exploited for food and medicine, their ethnomycological knowledge has not been documented in this ecosystem. Methods A field study was carried out between 2014 and 2015; 14 mushrooms used by the local communities were collected and identified using the polymorphism of the ribosomal ITS1, 5.8S, and ITS2 regions. Semi-structured questionnaires, focus group discussions, and pictorial method were used to collect information on edibility, local names, indigenous knowledge, and the role of macrofungi in ten communities. Results Ethnomycological findings revealed that mushrooms were used as food and medicine, while the non-edible species were regarded as food from Satan. Eight species, Polyporus tenuiculus, Termitomyces striatus, Termitomyces microcarpus Auricularia polytricha, Laetiporus sulphureus, Termitomyces sp.1, Termitomyces sp.2, and Polyporus dictyopus, were reported as edible and Auricularia polytricha, Daldinia concentrica, Ganoderma applanatum, Lentinus squarrosulus, Polyporus dictyopus, Termitomyces microcarpus, Trametes versicolor, Vascellum pretense and Xylaria sp., were used as medicine in traditional health care. Local names were found to be a very important factor in distinguishing between edible, medicinal, and poisonous mushrooms. Edible mushrooms are called “awo’oh” in Belo and “Kiwoh” in Oku. Poisonous mushrooms were commonly referred to as “awo’oh Satan” in Belo and “Kiwohfiyini” in Oku. Mushrooms were highly valued as a source of protein and as a substitute for meat in their diets. It is worth noting that Polyporus dictyopus was reported here for the first time in literature as an edible mushroom species. Conclusion Local knowledge of medicinal mushrooms in the treatment of different illness still exists in all ten villages surveyed. Elderly men and women appear to play an important role in primary health care services in these communities. This survey underscores the need to preserve and document traditional knowledge of the different medicinal mushrooms used in treating different illnesses and for more future scientific research on the mushrooms to determine their efficacy and their safety